The incidence of cardiovascular diseases in a population is correlated with the occurrence of a high blood cholesterol content. The blood cholesterol level has been found to be decreased by a diet, which contains specific food components. For example, it is recommended to eat fats with a high content of unsaturated fatty acids.
It is known further that particularly diets which contain olive oil are healthy, because olive oil consumption contributes to a good balance of HDL cholesterol and LDL cholesterol in the blood. Recently it has been found that some minor fat components particularly the anti-oxidants, including polyphenols from fat, positively interfere with the body's cardiovascular system, particularly because they are believed to help control oxidation of blood cholesterol. Non-refined olive oil has a high content of phenolic compounds which often are denoted as phenolics, polyphenols or, specifically, as olive phenolics or as olive polyphenols
Copending WO 99/32589 describes a useful application of said finding. The invention relates to spreads which contain olive oil as well as phenolic compounds. Traditionally for spread preparation an olive oil is employed which has been fully refined. The refining has removed together with the impurities also the beneficial phenolic compounds. Said patent application describes a refining process which is so mild that it delivers a purified oil from which undesired olive oil odour and most of the free fatty acids have been removed, but which still contains a considerable amount of healthy phenolic compounds.
The phenolics derived from olives form a group of chemical compounds, some of which have a relatively high oil solubility, the lipophilic olive phenolics, while others are more soluble in water, the hydrophilic olive phenolics. Only recently attention is given to the nutritional benefits of the hydrophilic polyphenols.
When olive oil is contacted with a water phase, e.g. during the usual water washing step, a partitioning of phenolic compounds occurs. A great part of the phenolic compounds is so hydrophilic that they easily migrate to the water phase, while the major part of the lipophilic phenolic compounds stay in the oil phase.
At least a part of the bitter taste of olive oil is ascribed to phenolic compounds. The lipophilic phenolic compounds which occur in the olive oil most contribute to the bitter taste.
In co-pending patent applications EP 849353 and EP 933419 olive oil processes are described, which aim at debittering the olive oil by removing and/or hydrolysing lipophilic phenolic compounds in olive oil. By hydrolysis the bitter lipophilic phenolic compounds are converted into the less bitter and more water soluble phenolic compounds. Since most of these migrate to the water phase of the olive oil/water mixture, they are removed when the separated water phase is discarded.
A characteristic sensoric property of many non-refined olive oils is astringency. The astringency is perceived as a non-pleasant feeling lingering in the back of the throat after some oil has been ingested. Excessive astringency, like excessive bitterness, spoils the taste of the oil. Astringency in olive oil appears to increase with its content of polyphenols.
WO 97/06697 teaches a healthy diet consisting of food products which have been fortified with high amounts of anti-oxidants, including phenolic compounds.
According to JP 59213368 (Derwent abstract) a tasty spread or cream is obtained by adding finely ground olives to food containing a fat-rich food ingredient. Because of the known astringent and bitter taste of olives, the olives are used only after a debittering treatment with sodium hydroxide solution.
It is known that after a sodium hydroxide treatment olives are substantially depleted with polyphenols. Therefore said process is not suited to enhance the content of phenolic compounds in a food product.
The aim of the present invention is to enhance the nutritional value of a food product by the addition of solid ingredients derived from olive fruits. Particularly vegetable oils, spreads, mayonnaises, salad dressings and sauces, in particular tomato sauces, may benefit from the invention. Particularly, the object of the present invention is to enrich food products with polyphenols from olive fruits.